The Global Systems for Mobile (GSM) communication is a globally accepted standard for digital cellular communication. GSM uses a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). Within each band are approximately one hundred available carrier frequencies on 200 kHz spacing (FDMA), and each carrier is broken up into time-slots so as to support eight separate conversations (TDMA). Each channel has an uplink and a downlink. GSM uses the Gaussian Minimum Shift Keying (GMSK) modulation method.
GPRS/EDGE is an extension of GSM technology and is applicable to data services. GSM uses Gaussian Minimum Shift Keying (GMSK) modulation and EGDE uses 8PSK Phase Shift Keying modulation.
The GSM/GPRS/EDGE frequency ranges are: 380–400 MHz, 410–430 MHz, 450–468 MHz, 478–496 MHz, 698–746 MHz, 747–792 MHz, 806–866 MHz, 824–894 MHz, 890–960 MHz, 880–960 MHz, 876–960 MHz, 870–921 MHz, and 1710–1990 MHz.
The instrument features two GSM/GPRS/EDGE measurement modes: RF Measurements (Option 40) and Demodulator (Option 41). The instrument can be directly connected to any GSM/GPRS/EDGE base station for accurate measurements. When a physical connection is not available or required, the instrument can receive and demodulate GSM/GPRS/EDGE signals over the air.
The spectrum view displays channel spectrum and multi-channel spectrum. The channel spectrum screen includes channel power, burst power, average burst power, frequency error, modulation type, and Base Station Identity Code (BSIC). The multi-channel spectrum displays as many as ten channels and, using the cursor to select a channel, can display the measurements for just the selected channel.
GSM/GPRS/EDGE Demodulator (Option 41) demodulates GSM/GPRS/EDGE signals and displays the results of detailed measurements to analyze transmitter modulation performance. Results are shown for phase error (rms), phase error peak, EVM (rms), EVM (peak), origin offset, C/I, modulation type and magnitude error (rms) and a vector diagram of the signal.
